Question about functions

Hello,
Where can i find list of all functions that Dude can handle ? like function ‘oid’, ‘oid_column’, ‘round’ etc. ?

I woluld like to round some number to - for ex. - dwo digits after dot, like 12.45 or 98.32 The Dude shows numbers with 6 digits after dot. Is there any way to do this ?

Regards.